Creatinine corrections for estimating children's and adult's pesticide intake doses in equilibrium with urinary pesticide and creatinine concentrations

Abstract

A urine contaminant concentration per se has uncertain meaning for human health because of dilution by hydration. However, the estimation of the health-related daily intake dose of pollutant (mg/kg/day) that equilibrates with a spot urinary concentration of a pesticide residue or metabolite, or other analyte, can be made using creatinine-corrected toxicant levels (mg analyte/mg creatinine) multiplied by an estimate of the subjects' expected creatinine excretion rates (mg creatinine/kg/day). The objective was to develop a set of equations predicting a person's expected daily creatinine excretion (mg/kg) as a function of age, gender, race and morphometry, from birth to old age. We review the creatinine excretion literature where infants, children and adults provided 24 h total urine samples for creatinine analysis. Equations are developed for infants (r3 years), children (3-18 years) and adults (Z18 years) that match at 3 and 18 years. A series of equations that estimate daily creatinine excretion (mg/day) are developed that are piecewise continuous from birth through infancy through adolescence and through adulthood for males and females, and Black and White races. Complicating factors such as diet, health status and obesity are discussed. We propose that these equations, with caveat, can now be used with measured urine concentrations to consistently estimate the corresponding equilibrium intake doses of toxicants at ages from birth to 92 years for the healthy non-obese. We recommend that this system of equations be considered for future development and reporting of applied doses in mg/kg/day of pollutants and toxicants that are measured in urine samples, as in the National Health and Nutrition Examination Survey.

Interpreting variability in population biomonitoring data: Role of elimination kinetics

“…Although substantial effort has been devoted to development of equations for prediction of creatinine excretion rates based on age, gender, body weight, and height (Mage et al 16,17 ), less information is available about within-individual variation in creatinine excretion rates. In the CDC data set, the coefficients of variation (CV) across the eight individuals for creatinine excretion rate in mg/h on a sample-by sample basis ranged from 24% to 50%.…”

Drinking water contribution to aggregate perchlorate intake of reproductive-age women in the United States estimated by dietary intake simulation and analysis of urinary excretion data

“…In this analysis, we have estimated perchlorate intake distributions from the NHANES data in a manner similar to that employed by Blount et al (2006) in analyzing the 2001-2002 data. Differences in our approach include: (1) we have estimated distributions for reproductive-age women instead of for all adult females, and (2) we have used an updated approach to adjust for differences in 24-h creatinine excretion which takes into account racial differences in excretion rates (Mage et al, 2008). In addition, we have generated two separate estimates of perchlorate intake, one based on the 2001-2002 data previously analyzed by Blount et al (2006) and another based on data from the 2003-2004 sampling rounds.…”

Assessment of Health Risk in Human Populations Due to Chlorpyrifos

“…When measured in units of mass/volume in the urine it is subjected to the variation of daily volume of urine eliminated by the person which can vary with hydration status. However the daily mass of creatinine excreted by a person is considered to be approximately constant [18,21]. Therefore it is assumed that the concentration, with creatinine correction, is a more reliable measurement, despite of the variations with different age groups, ethnicities etc.…”